The present invention pertains to microelectronic substrate polishing systems, to semiconductor wafer polishing systems, to methods of polishing microelectronic substrates, and to methods of polishing wafers.
During fabrication of microelectronic substrates, e.g. semiconductor wafers, the substrates can be polished through mechanical abrasion, as by chemical-mechanical polishing. During chemical-mechanical polishing, a substrate carrier typically holds a substrate while either or both of the substrate carrier and a polishing platen rotatably engage and thereby polish the substrate. Polishing of the substrate can be facilitated through the use of a polishing fluid or chemical slurry.
Some types of substrate carriers use vacuum pressure to hold a substrate on the substrate carrier. Of those types of substrate carriers, some use a resilient member which can engage the substrate in a suction-like configuration. Such suction can take place before, during, and/or after polishing. Exemplary carriers are described in U.S. Pat. Nos. 5,423,716, 5,449,316, and 5,205,082, the disclosures of which are incorporated by reference.
Of those types of carriers which use vacuum pressure to hold a substrate in place, problems can arise if a system malfunction allows polishing fluid or slurry to enter into the vacuum system. More specifically, in those types of vacuum systems that use a resilient member, a breach or tear in the resilient member can allow polishing fluid or slurry to enter into the vacuum system and possibly foul equipment such as pneumatic control systems and the like.
Accordingly, this invention arose out of concerns associated with providing improved microelectronic substrate polishing equipment and methods of polishing microelectronic substrates.
Microelectronic substrate polishing systems and methods of polishing microelectronic substrates are described. In one embodiment, a substrate carrier includes a resilient member and a vacuum mechanism. The vacuum mechanism is coupled to the substrate carrier and configured to develop pressure sufficient to draw a portion of the resilient member toward the substrate carrier. The drawing of the resilient member effects an engagement between the resilient member and a substrate which is received by the substrate carrier. A polishing fluid sensor is provided and coupled intermediate the resilient member and the vacuum mechanism. In another embodiment, the polishing fluid sensor is coupled intermediate the substrate carrier and the vacuum mechanism. In another embodiment, the vacuum mechanism comprises a vacuum conduit through which a vacuum is developed. The polishing fluid sensor can be mounted on or in the vacuum conduit. Various types of fluid sensors can be utilized, including resistive, capacitive, pressure-based, and/or photo detectors. In a preferred embodiment, the microelectronic substrate comprises a semiconductor wafer.